A computer system glitch left thousands of United Airlines passengers across the globe grounded Wednesday, causing a ripple effect of heavy delays throughout major airports.

About 3,500 flights were affected and the airline sought to recover after the ground stop was lifted. Aviation experts said that delays of even 90 minutes could have a snowball effect triggering flight delays at each late flight's destination.

"Its going to not only affect flights in air but all flights on the ground," Anthony Roman, a former pilot and president of Roman & Associates, a private investigation and risk-management consultancy told MSNBC. "They have flights in gates that should be occupied by another flight."

The delays could reach 235 domestic and 138 international destinations.